Environmental boundaries to save Gaia

September 26, 2009 at 2:14 am Leave a comment

If you’re wondering whether humans are stupid enough to be the architects of civilisation’s collapse and will become extinct….read on. Twenty eight scientists have been asked how we are going as stewards of Planet Earth. Really, why bother with twenty eight scientists when I could have given the short answer: humans are wrecking the planet and we will all be kaput!

Anyway, the pointy-headed scientists have drawn up a list of nine “planetary boundaries” that we had better not transgress if we, as a species, want to hang around and not suffer disastrous consequences. Check out this article from Nature for full details but basically, I’ll give you the goss – and the bad news? We’ve already crossed three of the planetary boundaries. Our planet’s environment has been unusually stable for the past 10,000 years. This stable period is known as the Holocene (aka The Long Summer) and has seen civilisations rise and fall. But since the Industrial Revolution, we’ve been in a new period – the Anthropocene – and basically the signature of this period is human activity driving environmental change, which could push us beyond the stability of the Holocene and into abrupt, irreversible climate change. So here is the framework the scientists propose to keep us within safe boundaries:

(1) Atmospheric concentration of carbon dioxide. Human changes to atmospheric CO2 concentrations should not exceed 350 parts per million by volume (p.p.m.v.) but current CO2 concentration stands at 387 p.p.m.v. and climbing. The boundary of 350 p.p.m.v. ensures the continued existence of the large polar ice sheets (but as we know, these are rapidly melting). So we’re probably toast as we’ve crossed this climate boundary already. The article says that we are already seeing evidence that some of Earth’s subsystems are moving outside their stable Holocene state eg accelerating rates of sea-level rise during the past 10–15 years and the retreat of mountain glaciers around the world.

(2) Biodiversity loss. This is the second boundary we’ve crossed and/or screwed up. Species extinction is a natural occurrence but biodiversity loss in the Anthropocene has accelerated massively and many scientists say we are in the grip of a sixth great extinction event. In 1993, Harvard biologist E.O. Wilson estimated that Earth is losing around 30,000 species per year (and this equates to three species per hour). Here’s a great site if you want to learn more about the mass extinction humans are causing. Today, the rate of extinction of species is estimated to be 100 to 1,000 times more than what could be considered natural.

(3) Nitrogen and phosphorus pollution. The rise of industrialised agriculture has thrown off Earth’s natural nitrogen and phosphorus cycles and we have pollution on land and in our water ways. We’ve passed the threshold with the nitrogen cycle because the planet and oceans simply can’t process the chemicals being dumped by humans obsessed with food production and cultivation of crops using chemicals. A major side-effect of nitrogen use is pollution of oceans – the Gulf of Mexico, for example, has a 5,800 square mile “dead zone” caused by nitrogen/fertilizer run off.

(4) Ozone. We haven’t stuffed this up because a 1987 ban on ozone-eating chemicals (being chlorofluorocarbons or CFCs) has resulted in atmospheric levels of ultraviolet radiation-blocking ozone now being at the safe level. Ozone depletion is a serious issue because it can lead to skin cancer, cataract and premature ageing of the skin.

(5) Freshwater use.  Demand for fresh water is soaring due to hygiene, sanitation, food production and industry. But planetary supplies of freshwater are dwindling. Current consumption for agricultural, for example, may expand from 2,600 cubic kilometers to 4,000 cubic kilometers in the future and this will lead to further environmental damage and water scarcity. Check out this freshwater scarcity map – it will freak you out:

Source: Scientific American

(6) Land use: I was reading the other day that Australia’s population growth is exploding (and given that we are the most arid continent on Earth, not sure this is smart). We will have 35 million by 2049 (current: 21,993,806 according to ABS). The world population is currently around 6.8 billion and is projected to surpass 9 billion by 2050. Just imagine: in 1950, the world population was 2.5 billion. To accommodate 9 billion people in 2050 you need land – so natural terrain, forests, fields and wetlands will most likely disappear to make way for cities and expanding suburbia. We’ll be lucky to spot a small shrub in the crowded concrete jungles of the future!

(7) Ocean acidification: Our civilisation oozes carbon dioxide and eventually it finds its way into waterways and oceans, raising their acidity levels. In acidic seawater coral, for example, have a tough time building their skeletons because the minerals they produce to build the skeletons quickly dissolve in acidic water. Apparently, oceans are now acidifying 100 times faster than at any time during the past 20 million years.

(8) Chemical pollution: I’m always saying that our era will be known as the “chemical generation” (that is if there are any humans left in the future).  We are chemical crazy. Go off and look at the ingredients in your shampoo…I’ll wait. Do you see Sodium Laureth Sulfate or Sodium Laurel Sulfate? If so, chuck it out now – these chemicals are known as surfectants and are basically foaming agents. They are known irritants and have also been linked to liver toxicity and may be carcinogenic. These chemicals also pop up in toothpaste, soap, mascara, laundry detergent, body wash, shave cream and so on. But you can get SLS-free products, go here for a list. Of course, nasty chemicals end up in our waterways and have been linked to genetic damage.

(9) Atmospheric aerosols. A volcano spewing forth its muck is likely to pollute the atmosphere but so are human-made sulfate aerosols created by the burning of coal and oil. Human-made sulfate aerosols are now thought to outweigh naturally produced sulfate aerosols such as desert dust and volcanic aerosols resulting from eruptions. Human-made sulfate aerosols are suspended in Earth’s atmosphere and actually have a cooling effect on climate but do not offset global warming.

Of the 9 planetary boundaries, we have crossed three. Below is the “planetary boundaries” table that shows the sorry state of affairs.

Click here for larger view (Source: Nature).

Entry filed under: Climate Change, Education and Awareness, Environment, Nature, Useful resources.

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